Neuronal integration across senses: Psychophysical and computational approaches to cue integration in injured brain

这个项目将研究导致意识体验的感觉整合的特征和神经元基础。特别是，我们感兴趣的是视觉和听觉系统之间的相互作用，从而导致对事件的感知。信号检测理论为研究跨感官的刺激检测提供了坚实的基础。给定感官系统(例如，听觉或视觉)，我们可以量化所需的信号水平(光强度或声音幅度)，以便与背景区分并因此被检测。然后，检测能力被表示为该意义上的刺激强度的概率函数。如果组合两个信号(例如，光和声音两者)，则总体检测概率不同于分别从每个感测预期的检测概率。这种改进的性能被称为冗余增益。一些计算建模方法被用来理解冗余收益背后的机制(例如，Otto等人，2013年)。这些方法是(单一感觉)证据积累框架的扩展，适用于两个感官刺激为知觉决定提供证据的情景。他们使用反应时间数据和错误率来提取加工的各个阶段，如信息获取、偏差、决策标准或非决策成分，这些成分在基于感觉加工的决策中受到影响。有趣的是，所有这些都依赖于探测能力，而不是意识。一个重要的发现是探测和意识的分离(Weiskrantz，2009)。这与脑损伤患者尤其相关，他们在没有意识到刺激的情况下(称为失明或失聪)，检测到信号的几率可能要高得多。有趣的是，反复暴露在感官刺激下可以导致敏感度的提高和功能的恢复，例如，在使用阈值以上的多感官刺激进行系统刺激后观察到了这一点(Bologinei等人，2005年)。如果得到证实，这种多感觉刺激可能会为脑损伤后的康复带来新的技术。为了研究多感觉输入对神经元可塑性的影响，该项目是一个合作项目，结合了三位主管的心理物理学、计算模型和临床神经科学的专业知识。该项目将使用心理物理调查，在报告的意识意识的背景下检查视听互动。我们将开发和应用与已报道的知觉相关的计算模型，以找出加工的哪些方面可能受到多感觉输入的影响。此外，我们打算招募脑损伤(中风幸存者)的参与者，这些参与者的主要视觉或听觉皮质区域都有损害，以检验模型预测。这些对感觉过程的神经元编码的基础研究对于形成未来康复技术的坚实基础至关重要。

This project will investigate the characteristics and neuronal underpinning for sensory integration leading to conscious experience. In particular, we are interested in interactions between visual and auditory systems leading to awareness of events. Signal Detection Theory has provided a solid ground to investigate stimulus detection across senses. Given a sensory system (e.g., audition or vision), we can quantify the level of signal that is needed (the light intensity or the sound amplitude) to be distinguished from the background and therefore to be detected. The detection capacity is then expressed as a probability function of the stimulus strength in that sense. If two signals (e.g., both light and sound) are combined, then the overall detection probability is different than that expected from each sense separately. This improved performance is termed redundancy gain. A number of computational modelling approaches have been used to understand the mechanisms underlying redundancy gains (e.g., Otto et al., 2013). These approaches are extensions of the (unisensory) evidence accumulation framework to a scenario in which two sensory stimuli provide evidence for a perceptual decision. They use reaction time data and error rates to distil the stages of processing such as information uptake, bias, decision criteria or non-decisional components that are affected in decision making based on sensory processing. Interestingly, all the above are reliant on detection capacity and not conscious awareness.An important discovery has been the dissociation of detection and awareness (Weiskrantz 2009). This is particularly relevant in patients with brain injury, who may be significantly above chance in detecting a signal whilst having no conscious experience of a stimulus (labelled blindsight, or deaf-hearing). Interestingly, repeated exposure to sensory stimuli can lead to increased sensitivity and recovery of function, which was observed for example after systematic stimulation using supra-threshold multi-sensory stimuli (Bolognini et al 2005). If confirmed, such multi-sensory stimulation could lead to new techniques for rehabilitation after brain injury.To study the influence of multi-sensory input on neuronal plasticity, the proposed project is a collaborative effort combining expertise from psychophysics, computational modelling, and clinical neuroscience of the three supervisors. The project will examine audio-visual interaction in the context of reported conscious awareness using psychophysical investigation. We will develop and apply computational models in relation to reported awareness to find out which aspects of processing could be affected by multi-sensory input. In addition, we intend to recruit participants with brain injury (stroke survivors) with lesions in either primary visual or auditory cortical areas in order to examine the model predictions. These basic investigations on neuronal encoding of sensory processes are crucial in forming a solid foundation for future rehabilitation techniques.